1. Field of the Invention
The present invention relates to a self-routing packet switching system.
2. Description of the Prior Art
In a prior art packet switching system, the address of a packet given from an input line is identified. Then the packet is supplied to an output line corresponding to the desired address. When a plurality of packets destined for the same address are simultaneously entered into such a packet switching system, the switching of the competing packets can be achieved in one of the following two methods. By one method, a sorting network and a routing network are combined. The competing packets are dropped and given appropriate delays in a later stage of the routing network. Then they are reentered into the same routing network as taught by Alan Huang et al. in an article entitled "A Wideband Digital Switch" published in 1984 in the IEEE Global Telecommunications Conference Record. By the other, a switch module having an n-input one-output selecting function is provided for each corresponding output line. Switching is accomplished so as to select the packet destined for a given output line from signals appearing on a bus comprising n-input lines as disclosed by Y. S. Yeh et al. in an article entitled "The Knockout Switch: A Simple, Modular Architecture for High-Performance Packet Switching" published in the Proceedings of the IEEE International Switching Symposium 1987.
The first method however, requires complex processing, such as time queueing, in order to avoid reversing of the sequence of the competing packets when they are reentered. The second method needs a number of n-input one-output (n is the number of input lines) switch modules which is equal to the number of output lines, which entails a large volume of hardware if many input and output lines are involved.